@article{vonKriesWeissFalkenhorstetal.2011,
  author    = {von Kries, R{\"u}diger and Weiss, Susanne and Falkenhorst, Gerhard and Wirth, Stephan and Kaiser, Petra and Huppertz, Hans-Iko and Tenenbaum, Tobias and Schroten, Horst and Streng, Andrea and Liese, Johannes and Shai, Sonu and Niehues, Tim and Girschick, Hermann and Kuscher, Ellen and Sauerbrey, Axel and Peters, Jochen and Wirsing von Koenig, Carl Heinz and R{\"u}ckinger, Simon and Hampl, Walter and Michel, Detlef and Mertens, Thomas},
  title     = {Post-Pandemic Seroprevalence of Pandemic Influenza A (H1N1) 2009 Infection (Swine Flu) among Children < 18 Years in Germany},
  series = {PLoS ONE},
  volume    = {6},
  journal   = {PLoS ONE},
  number    = {9},
  doi       = {10.1371/journal.pone.0023955},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-141698},
  pages     = {e23955},
  year      = {2011},
  abstract  = {Background: We determined antibodies to the pandemic influenza A (H1N1) 2009 virus in children to assess: the incidence of (H1N1) 2009 infections in the 2009/2010 season in Germany, the proportion of subclinical infections and to compare titers in vaccinated and infected children. Methodology/Principal Findings: Eight pediatric hospitals distributed over Germany prospectively provided sera from in-or outpatients aged 1 to 17 years from April 1(st) to July 31(st) 2010. Vaccination history, recall of infections and sociodemographic factors were ascertained. Antibody titers were measured with a sensitive and specific in-house hemagglutination inhibition test (HIT) and compared to age-matched sera collected during 6 months before the onset of the pandemic in Germany. We analyzed 1420 post-pandemic and 300 pre-pandemic sera. Among unvaccinated children aged 1-4 and 5-17 years the prevalence of HI titers (>= 1:10) was 27.1\% (95\% CI: 23.5-31.3) and 53.5\% (95\% CI: 50.9-56.2) compared to 1.7\% and 5.5\%, respectively, for pre-pandemic sera, accounting for a serologically determined incidence of influenza A (H1N1) 2009 during the season 2009/2010 of 25,4\% (95\% CI : 19.3-30.5) in children aged 1-4 years and 48.0\% (95\% CI: 42.6-52.0) in 5-17 year old children. Of children with HI titers >= 1: 10, 25.5\% (95\% CI: 22.5-28.8) reported no history of any infectious disease since June 2009. Among vaccinated children, 92\% (95\%-CI: 87.0-96.6) of the 5-17 year old but only 47.8\% (95\%-CI: 33.5-66.5) of the 1-4 year old children exhibited HI titers against influenza A virus (H1N1) 2009. Conclusion: Serologically determined incidence of influenza A (H1N1) 2009 infections in children indicates high infection rates with older children (5-17 years) infected twice as often as younger children. In about a quarter of the children with HI titers after the season 2009/2010 subclinical infections must be assumed. Low HI titers in young children after vaccination with the AS03(B)-adjuvanted split virion vaccine need further scrutiny.},
  language  = {en}
}
@article{StrengGroteLiese2011,
  author    = {Streng, Andrea and Grote, Veit and Liese, Johannes G.},
  title     = {Severe influenza cases in paediatric intensive care units in Germany during the pre-pandemic seasons 2005 to 2008},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69120},
  year      = {2011},
  abstract  = {Background: Data on complications in children with seasonal influenza virus infection are limited. We initiated a nation-wide three-year surveillance of children who were admitted to a paediatric intensive care unit (PICU) with severe seasonal influenza. Methods: From October 2005 to July 2008, active surveillance was performed using an established reporting system for rare diseases (ESPED) including all paediatric hospitals in Germany. Cases to be reported were hospitalized children < 17 years of age with laboratory-confirmed influenza treated in a PICU or dying in hospital. Results: Twenty severe influenza-associated cases were reported from 14 PICUs during three pre-pandemic influenza seasons (2005-2008). The median age of the patients (12 males/8 females) was 7.5 years (range 0.1-15 years). None had received vaccination against influenza. In 14 (70\%) patients, the infection had been caused by influenza A and in five (25\%) by influenza B; in one child (5\%) the influenza type was not reported. Patients spent a median of 19 (IQR 12-38) days in the hospital and a median of 11 days (IQR 6-18 days) in the PICU; 10 (50\%) needed mechanical ventilation. Most frequent diagnoses were influenza-associated pneumonia (60\%), bronchitis / bronchiolitis (30\%), encephalitis / encephalopathy (25\%), secondary bacterial pneumonia (25\%), and ARDS (25\%). Eleven (55\%) children had chronic underlying medical conditions, including 8 (40\%) with chronic pulmonary diseases. Two influenza A- associated deaths were reported: i) an 8-year old boy with pneumococcal encephalopathy following influenza infection died from cerebral edema, ii) a 14-year-old boy with asthma bronchiale, cardiac malformation and Addison's disease died from cardiac and respiratory failure. For nine (45\%) patients, possibly permanent sequelae were reported (3 neurological, 3 pulmonary, 3 other sequelae). Conclusions: Influenza-associated pneumonia and secondary bacterial infections are relevant complications of seasonal influenza in Germany. The incidence of severe influenza cases in PICUs was relatively low. This may be either due to the weak to moderate seasonal influenza activity during the years 2005 to 2008 or due to underdiagnosis of influenza by physicians. Fifty \% of the observed severe cases might have been prevented by following the recommendations for vaccination of risk groups in Germany.},
  subject      = {Deutschland},
  language  = {en}
}